package czk.concrent.juc.semaphore.practice;

import java.sql.*;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicIntegerArray;

/**
 * @Author:ChenZhangKun
 * @Date: 2020/12/30 20:51
 */
public class SemaphoreDataSource {
    public static void main(String[] args) {
        ConnectionPool pool=new ConnectionPool(20);
        for (int i = 0; i < 10; i++) {
            new Thread(()->{
                // 借连接
                Connection connection=pool.borrow();
                // 休眠
                try {
                    TimeUnit.SECONDS.sleep(2);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                // 还连接
                pool.backConnection(connection);
            }).start();
        }
    }
}

class ConnectionPool {
    /**
     * 大小
     */
    private int size;
    /**
     * 连接数组
     */
    private Connection[] connections;
    /**
     * 状态数组
     */
    private AtomicIntegerArray atomicIntegerArray;
    /**
     * 设置最多去连接的数目
     */
    private Semaphore semaphore=new Semaphore(3);

    /**
     *
     * @param size
     */
    public ConnectionPool(int size) {
        this.size = size;
        // 初始化连接
        connections=new Connection[size];
        // 初始化状态数组
        atomicIntegerArray=new AtomicIntegerArray(new int[size]);
        // 填充连接
        for (int i = 0; i < size; i++) {
            connections[i]=new MockConnection();
        }
    }

    /**
     * 去连接
     * @return
     */
    public Connection borrow(){
        try {
            // 技术减一
            semaphore.acquire();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        // 取连接
        for (int i = 0; i < size; i++) {
            // 拿到状态 0 空闲 1 繁忙
            int status = atomicIntegerArray.get(i);
            if (status==0){
                // 将其改为繁忙
                if (atomicIntegerArray.compareAndSet(i,0,1)){
                    // 返回连接
                    System.out.println("拿到连接");
                    return connections[i];
                }
            }
        }
        return null;
    }

    /**
     * 归还连接
     * @param connection
     */
    public void backConnection(Connection connection){
        for (int i = 0; i < size; i++) {
            if (connections[i]==connection){
                // 将其设置为0
                atomicIntegerArray.set(i,0);
                // 释放
                semaphore.release();
                System.out.println("释放连接");
                break;
            }
        }
    }
}

/**
 * 连接
 */
class MockConnection implements Connection {

    @Override
    public Statement createStatement() throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql) throws SQLException {
        return null;
    }

    @Override
    public CallableStatement prepareCall(String sql) throws SQLException {
        return null;
    }

    @Override
    public String nativeSQL(String sql) throws SQLException {
        return null;
    }

    @Override
    public void setAutoCommit(boolean autoCommit) throws SQLException {

    }

    @Override
    public boolean getAutoCommit() throws SQLException {
        return false;
    }

    @Override
    public void commit() throws SQLException {

    }

    @Override
    public void rollback() throws SQLException {

    }

    @Override
    public void close() throws SQLException {

    }

    @Override
    public boolean isClosed() throws SQLException {
        return false;
    }

    @Override
    public DatabaseMetaData getMetaData() throws SQLException {
        return null;
    }

    @Override
    public void setReadOnly(boolean readOnly) throws SQLException {

    }

    @Override
    public boolean isReadOnly() throws SQLException {
        return false;
    }

    @Override
    public void setCatalog(String catalog) throws SQLException {

    }

    @Override
    public String getCatalog() throws SQLException {
        return null;
    }

    @Override
    public void setTransactionIsolation(int level) throws SQLException {

    }

    @Override
    public int getTransactionIsolation() throws SQLException {
        return 0;
    }

    @Override
    public SQLWarning getWarnings() throws SQLException {
        return null;
    }

    @Override
    public void clearWarnings() throws SQLException {

    }

    @Override
    public Statement createStatement(int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    @Override
    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency) throws SQLException {
        return null;
    }

    @Override
    public Map<String, Class<?>> getTypeMap() throws SQLException {
        return null;
    }

    @Override
    public void setTypeMap(Map<String, Class<?>> map) throws SQLException {

    }

    @Override
    public void setHoldability(int holdability) throws SQLException {

    }

    @Override
    public int getHoldability() throws SQLException {
        return 0;
    }

    @Override
    public Savepoint setSavepoint() throws SQLException {
        return null;
    }

    @Override
    public Savepoint setSavepoint(String name) throws SQLException {
        return null;
    }

    @Override
    public void rollback(Savepoint savepoint) throws SQLException {

    }

    @Override
    public void releaseSavepoint(Savepoint savepoint) throws SQLException {

    }

    @Override
    public Statement createStatement(int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    @Override
    public CallableStatement prepareCall(String sql, int resultSetType, int resultSetConcurrency, int resultSetHoldability) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int autoGeneratedKeys) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, int[] columnIndexes) throws SQLException {
        return null;
    }

    @Override
    public PreparedStatement prepareStatement(String sql, String[] columnNames) throws SQLException {
        return null;
    }

    @Override
    public Clob createClob() throws SQLException {
        return null;
    }

    @Override
    public Blob createBlob() throws SQLException {
        return null;
    }

    @Override
    public NClob createNClob() throws SQLException {
        return null;
    }

    @Override
    public SQLXML createSQLXML() throws SQLException {
        return null;
    }

    @Override
    public boolean isValid(int timeout) throws SQLException {
        return false;
    }

    @Override
    public void setClientInfo(String name, String value) throws SQLClientInfoException {

    }

    @Override
    public void setClientInfo(Properties properties) throws SQLClientInfoException {

    }

    @Override
    public String getClientInfo(String name) throws SQLException {
        return null;
    }

    @Override
    public Properties getClientInfo() throws SQLException {
        return null;
    }

    @Override
    public Array createArrayOf(String typeName, Object[] elements) throws SQLException {
        return null;
    }

    @Override
    public Struct createStruct(String typeName, Object[] attributes) throws SQLException {
        return null;
    }

    @Override
    public void setSchema(String schema) throws SQLException {

    }

    @Override
    public String getSchema() throws SQLException {
        return null;
    }

    @Override
    public void abort(Executor executor) throws SQLException {

    }

    @Override
    public void setNetworkTimeout(Executor executor, int milliseconds) throws SQLException {

    }

    @Override
    public int getNetworkTimeout() throws SQLException {
        return 0;
    }

    @Override
    public <T> T unwrap(Class<T> iface) throws SQLException {
        return null;
    }

    @Override
    public boolean isWrapperFor(Class<?> iface) throws SQLException {
        return false;
    }
}
